Constant frequency oscillator



June 4, 1935. E. KOCH CONSTANT FREQUENCY OSCILLATOR Filed April 16, 1932 2 Sheets-Sheet l ll Alw INVENTOR E627! LJfOC/Z ATTORN EY June 4,1935. 5 L K H 1 2,003,371;

CONSTANT FREQUENCY OSCILLATOR 'FiledxA pril 16, 1932 2 Sheets-Sheet 2 g 63 E 55 I 60 9' '1 141 1 5 v f w 1 1 :55 f I I g; 2 g? E E s .5 3 E E 64 i w INVENTOR' Earl Ljloch 5 is the degree of constancy of the, transmitter freoscillator described herein the varia Patented June 4, 1935 V :1 i

UNITED STATES PATENT I.

2,003,371 CONSTANT FREQUENCY OSCILLATOR Earl L. Koch, Chicago, Ill., assignor, by me'sne assignments, to Earl'L. Koch Holding Corporation, New York, N; Y., a corporation of New York 7 Application AprlllG, 1932, Serial No. 605,644 I 6 Claims; (01. 250-36) This invention relates to improvements in oseil- The general conclusion by those skilled in this lators, and is directed more particularly to conart is that changes in the grid current are reamin stant frequency oscillators employing electronic sible for the instability of this type of oscillator. devices having control elements outside the glass Even in tubes of the high vacuum types there 5 envelope such-as described inapplications, Serial exist a considerable number ofresidual gas mol e- Number 524,254, filed March 21,1931, Serial Numcules capable of being ionized and causing ber 566,008, filed September 30,1931, Serial Numgrid current to vary and give erratic results.

ber 568,552, filed October 13, 1931 and Serial No. The plate current generaiiy measured in Lfi d Ap 19 those o n an llia es h l he ri curre i m as d de cr d nn e m Q m am a ,thc e ere ihq ii In radio communication, it is important that a more susceptible to minute changes space constant source of frequency be provided. This charge resulting from molecular-cgllision the is particularly true in radio telephony because tube. V v the only limit to the closeness of channel spacing In the new and improved constant ireguency quency. V mentioned are eliminated and the cirfi uit; due

The present standard of constant frequency the use of an external gridtype of tube-,isgreatgenerator is the piece-electric crystal controlled ly simplified by eliminating semeof theins uoscillator in which the fr qu ncy of the generated mentalities heretofore used in oscillators en -p lpy 20 oscillation depends upon the physical dimensions ing vacuum tubes. 20

45 cuit with opposite temperature coeilicients so that an outside grid or control element;

of the crystal. This crystal is nadeofquartaand This type of oscillator gives results quiteeoms b tem u c trc to m i t in c ar t t bes qua c y ta cil atq s, ta dimens a d on ent c nst n eo t t in erentdisad a a e o th s sba quency. This type of oscillator has disadvansuch are described above, .andpossesses jezgtreme 5 tages in that the crystals are costly, they are flexibility in that the output frequencymay Subject toerratic eha ior due o chan s in e han d t s me o he v ueb ch n in 9.11m crystalline structure, and they are inflexible, a the circuit components, generally the capacity p a s al f rent d me sie t i of the smd a err necessary for each desiredfrequeney. An object of the invention is the provision of In frequency oscillators usingthe present types a constant frequency oscillator having a minie 3g.

of hr n ou elem n ac um u es, he u of c u omncn tsaad cn e a min use of the n i l o ene atien i c ed t m um points i t circuit w ic the point of sustained sciilati n generation. variations can occur. r

Variations in frequency in such systems may be A further object of the invention is the pro oughl d de into tw cla se those Occurring vision o a c n t re n y cillat r emp w- 35 in the tube per se and the power supply coning a vacuum tube in which the control element nected thereto, ,andthoseocc rring in theassois not in the path of the electron stream, within ciated circuit or the instrumentalities therein. the bulb thereof. Variations in th cir uit; ar ue princi all s oth objects nd d a e h inventio 40 changes in temperature, resulting in changes in disclosed herein will be apparent to those skilled 40 the L, C and R constants of the circuit. By temin the art. i V H perature controlling the instrumentalities and Referring to theudrawings: the connections-thereto in the oscillatory circuit, Figure 1 is a diagram of one embodiment of or byde is n th an 0 n ta t o the: 9 7- he vnren icn emp oyin a va umtuhe havi the LC value is maintained over a wide range of Figure 2 is an elevation, partly in section,

temperature, thesechangesmay be reduced or showing a simple form of external'grid tube practically eliminated. which was successfully as a constant ire,-

It is also possible to maintain the filament and quency oscillator;

- plate voltages at practically constant values. Figure 3 is a view of Figure ;2 as viewed along 5i) ve n twit s andin th ta h al c e l n +3 1 th e pr an a eta n it i bua t at i i ur v s a e on iew al n th 1 m the typ o i a e: th an .feu e r s; l mea tub the cu es frequ ncy d es amro t lera cana lv nseetiom 55, van, 7 a i v of another type of external grid tubeiwhi'qhgives a above 15,

' nected to one side of the filament 2|, A variable excellent results as an oscillator when used as herein disclosed;

Figure 6 is a section along the line 66 of Figure 5;

Figure 7 is a view taken along the line of Figure 5;

Figure 8 is a front elevation of another type of external grid tube in which the plate is shielded against grid plate capacity by the presence of the filament therebetween;

Figure 9 is a section along the line 9--9 of Figure 8; and 7 Figure 10 is a view taken along the line Ill -l0, Figure 8.

n In Figure 1, an electronic device designated generally by the numeral 20, havinga filament or cathode 2| and a plate or anode 22 within the envelope and a grid or control element 23 outside the envelope is connected up to function as an oscillator.. The filament 2| is connected to a suitable source of current 24, and the grid 23 and the plate 22 are connected together via an inductance 25, the grid 23 being connected to the inductance 25 at the point indicated by the numeral 26 and the plate 22 being connected thereto at 21. f n

A suitable plate current supply 29 has its positive terminal connected to 28, the mid-tap of the inductance 25, and its negative terminal concondenser 3|), isshunted across the terminals of the-inductance 25 forming a tank circuit. A suitable by-pass condenser 3| is connected between thenegative side of the filament and the wire leading to the mid-tap 28, or in parallel with the plate supply 29. I

' The frequency of this oscillator may be changed to difierent values by varying the capacity of the condenser 20;

It will be noted that the grid 23 is maintained at a high positive potential, even at substantially the same potential as that impressed upon the plate 22, no blocking condensers, grid leaks or C bias being necessary, and the absence of these parts from the circuit eliminates the possibilities of variations which they could cause therein.

The absence of the grid from the path of the electron stream within the tube and the formation of a cloud of electrons inside the bulb wall of the tube in the area embraced by the outside grid makes it possible to operate this oscillator with the plate and the grid at substantially the same (positive) potential.

In this circuit a tube having the control element outside of the envelope may be used. One form of tube suitable for this purpose is shown in Figures 2, 3 and 4 in which a filament or cathode 32 is supported by members 33 and 34 which are secured inthe press of the stem 35.

Connections to these members for supplying current to the filament 32 are shown at 38 and 39.

An anode or plate 36 is positioned adjacent to the cathode 32 and is carried by an extension of the wire 40 which is also supported by the press of the'stem 35. 7

- These elements are surrounded by a glass envelope 31 which is sealed to the stem 30.

A grid or control element 4| which snugly fits theenvelope 31 is positioned substantially in line Another form of tube suitable for use as a constant frequency oscillator is shown in Figures 5, 6 and 7, where a cathodeor filament 43 of helical or any other suitable form is supported by the members 44, 45 passing through the press of the stem 48 and the connections thereto are shown at 46 and 41 respectively.

An anode or plate 49 is positioned opposite to the filament 43 and is carried by the member 50 which is supported by the press of a second stem 5| and the connection thereto is shown at 55.

An enclosing glass envelope 52 has the stems 48 and 5| sealed thereto at opposite ends thereof with the cathode 43 and the anode 49 positioned therein oppositely.

A control element 53 fits snugly around the envelope 52 and a connection thereto is shown at 54.

Figures 8, 9 and 10 show another type of tube suitable for use as a constant frequency oscillator in which an anode or plate 56 is carried by members51 and 58 which are supported by the press of the stem 59. An extension 69 of the member 51 serves as a connection for the plate 56.

A cathode or filament 6|! surrounds the plate 56 and is preferably concentric therewith. This filament is carried by members 6| and 62 and extensions 5! and 58 respectively thereof form connections to the filament. A disc 63 may be provided on the end of the member 6| as a shield for the filament. r r

A glass envelope 64 is sealed to the stem 58 in substantially concentric relation to the plate and filament therein.

A grid or control element 65 fits snugly around the outside of the envelope 64 and a connection to this grid 65 is shown at 66.

The electronic device described in application Serial No. 605,645, filed April 16, 1932, is also readily adapted for use as a constant frequency oscillator as outlined above.

It is obvious that other oscillating circuits than the one shown and described may be used with the types of electronic devices herein described and referred to without departing from the invention as recited in the appended claims.

What is claimed is:

1. In an oscillator, an electronic device including an evacuated envelope having contained therein an anode and a cathode, an electro-static control element or grid located external to said envelope, a resonating circuit comprising a tapped inductance with capacity in parallel connected directly between said anode and grid, and means including a power source for'supplying a positive potential to said grid and anode with respect to said cathode through said inductance tap, also means for heating said cathode for the purpose of establishing an electron stream between said cathode andanode.

2. In' an oscillator, an electronic device including a grid, anode and cathode, said anode and cathode being located within an evacuated envelope and said grid being located external to said envelope, an inductance directly connecting said grid and anode, a capacity in parallel with said inductance, said inductance having a tapped connection, a source of current supplying a positive potential to said grid and anode with respect to said cathode through said inductance tap, and

a source of power'for heating said cathode to cause electron emission therefrom.

3. In an oscillator, an electronic device including a container, an externally located grid and a plate and a filament located within said con:

tainer, means for heating said filament, a center tapped inductance shunted with a variable capacity directly connecting said grid and plate, and a source of current for impressing a negative potential upon said filament and a positive potential upon said grid and plate through said center tap of said inductance.

4. In an oscillator, an electronic device including an evacuated container having plate and filament elements located therein and a grid element located external to said container and electronically isolated from said plate and filament elements, means for heating said filament, an inductance connected directly between said grid and plate, said inductance having a midtap, a capacity also connected directly between said grid and plate, and a source of current connected from said filament to the mid-tap of said inductance with positive polarity to said mid-tap.

5. In an oscillator, an electronic device including an envelope having a plate and filament therein, a grid positioned around the outside of said envelope, means for heating said filament, an inductance connected to said grid and plate, said inductance having a mid-tap, a capacity also connected to said grid and plate, and a source of current connected from said filament to the midtap of said inductance.

6. In an oscillator, an electronic device including an envelope having a plate and filament therein, a grid positioned around the outside of said envelope, means for heating said filament,

an inductance connected to said grid and plate,

said inductance having a tapped connection, a variable capacitor also connected to said grid and plate, and a source of current connected from said filament to the tapped connection of said inductance.

EARL L. KOCH. 

